1. Field of the Invention
This invention relates to stents of improved configuration.
2. Brief Description of the Prior Art
Stents are radially expandable endoprosthesis which are typically intravascular implants capable of being implanted transluminally and enlarged radially after being introduced percutaneously. They have also been implanted in urinary tracts and bile ducts. They are used to reinforce body vessels and to prevent restenosis following angioplasty in the vascular system. They may be self-expanding or expanded by an internal radial force, such as when mounted on a balloon.
In the past, stents have been generally tubular but have been composed of many configurations and have been made of many materials, including metals and plastic. Ordinary metals such as stainless steel have been used as have shape memory metals such as Nitinol and the like. Stents have also been made of biodegradable plastic materials. Such stents have been formed from wire, tube stock, etc. Some stents are self-expanding and some are expanded by an interior radial force.
This invention provides new configurations of the segments making up stents which may be adapted to all of the various types of prior art stents described above and/or known previously in the art. There are numerous advantages to the new configurations. For example, the configurations of the invention limit recoil and add resistance to compression for an expanded stent, among other things. Also, the stents of this invention are longitudinally flexible.
The inventive stents comprise a plurality of annular elements aligned to form a cylindrical stent body. Each annular element, in turn, is comprised of a plurality of open, generally boomerang-shaped segments. The segments are interconnected top-to-bottom around each of the annular elements. Adjacent annular elements are interconnected by one or more interconnecting elements. Each interconnecting element extends from an end of a boomerang-shaped segment in one annular element to an end of a boomerang-shaped segment in an adjacent annular element. In a preferred embodiment an interconnecting element extends from each boomerang-shaped segment in an annular element to a neighboring boomerang-shaped segment in an adjacent annular element.
Interconnecting elements joining adjacent annular elements are desirably U-shaped or zig-zag shaped, although other curvilinear and rectilinear interconnecting elements may also be used.
Adjacent boomerang-shaped segments in an annular element may be interconnected via a link extending from the top of a segment to the bottom of an adjacent segment. The links may range in design from a short, straight connector to any of the shapes described below for the interconnecting elements.